Well, I can tell you your Liberian character is going to have to be young, because people don't live to be very old there.

I think with the character in Inglorious Basterds, that guy was trained to look for that kind of thing. A. it's a war, and B. he was high ranking SS, right? Like the main Nazi (I forget his name), he was probably trained to look for that sort of thing. In other words, I wouldn't worry too terribly much.
(That said, there are a few glaring things for every culture, like wearing white socks.)